Telegraph signal regenerating apparatus



A. F. coNNl-:RY 2,118,069

TELEGRAPH SIGNAL REGENERAT'ING APPARATUS Filed July 25, 195e 2 sheets-sheer 1 May 24, 1938.

.VII 08S May 24, 1938. A. F. coNNERY 2,118,059

TELEGRAPH SIGNAL REGENERATING APPARATUS 2 Sheets-Sheet 2 Filed July 25, 1956 mgm maga/IL non mw xm man muv .NGE

lNvaN-ron 6105/? /v- Cown/wy ATTORNEY Patented, May 24, 1/938 UNITED STATES "PATENT OFFICE TELEGRAPH SIGNAL REGENERATING APPARATUS Application July 25,\l936, Serial No. 92,551

y Claims.

Marion H. Woodward, iiled July 1, 1936, Ser. No.

It is an object of the present invention to provide an improved generator circuit in which the Y w various characteristics of the circuit are readily adjustable.

It is also an object of the invention to provide an improved fork correcting circuit of the type in which corrections of a predetermined duration i.; are applied to the fork when the phase of the fork and of the signal diier from each other by more than a predetermined amount. More particularly, it is an object to provide such a fork correcting circuit in which the above mentioned predetermined duration of the corrections is measured by a reliable, accurate circuit which is readily adjustable and whose time constant is independent of the rapidity with which the corrections recur. Another particular object of the invention is to 23 provide such a fork correcting circuit in which the predetermined amount of phase difference between the signal pulses and the fork contact closures is also measured by a readily adjustable circuit having the desirable characteristics of re- 30 liability, accuracy and constancy of time.

The invention may be best understood by reference to the drawings, in which Fig. 1 and Fig. 2, when placed together, form a schematic representation of one preferred forni of regenerator in 35 accordance with the present invention. In the drawings, is an incoming cable over which signals are received from a distant transmitter (not shown). It will be assumed that the signals are in the so-called Submarine Morse" code in which 40 the dots and dashes consist of positive and negative pulses oi' equal length and in which zero or no current intervals of this same length are used for spaces between letters and words. It will also be assumed that the signals are trans- 45 mitted at `a substantially constant rate as from a tape transmitter.

Relay 2 is a receiving relay of the moving coil type which normally stands with its contact lever midway between its two contacts and is polarized ,3o so that it will be actuated to the rig'ht by a signal pulse of positive current (a dot) and to the left by a-signal pulse of negative current (a dash).

For convenience in reading the drawings, the

l winding of this relay 2 has been arranged so that 55 acurrent whose conventional direction through the winding is from left to right in the drawings will cause the armature of the relay to move in the same direction, that is, fromieft to right. This same arrangement has been followed with respect to every winding of every polarized relay in both figures of drawings, so that in general the same simple rule may be applied in studying the operations of any of the polarized relays. A current from left to right will move the armature from left to right and vice versa..

Connected to the contacts of receiving relay 2 are the operating windings |03, 04 of the dot and dash locking relays 3 and l', respectively. These relays 3 and 4 are also provided with biasing windings 203, 204, respectively, through which current is applied to bias the armatures toward the left, as shown in the drawings. Each of these relays is also provided with two locking windings 303, 403, 304 and 4104, respectively. These locking windings are so connected in series with the contacts of the relays 3 and 4, that the relays are locked in whichever position they happen to occupy, whenever current is owing through the relay contacts. Connected to the contacts of the dot and dash locking relays, respectively, (and in series with the above mentioned locking windings) are the operating windings |05, 205 and |06, 206 of dot and dash transmitting relays 5 and 5. These transmitting relays 5 and 6 have no predetermined bias in any particular direction but are provided with senil-locking windings 305, 306 which are so connected to the contacts of the relays themselves that the relays are partially locked in whatever position they happen to be. None of these semi-locking windings, however, produces a strong enough locking bias to prevent therelay from moving to a new position when the appropriate operating winding is energized. The contacts of transmitting relays 5 and 6 are connected to a special ungrounded transmitting battery and the armatures of the relays are connected to the outgoing cable 8 and to the outgoing ground connection, as shown in Fig. 2.

The above described chain of apparatus performs the function of retransmitting to outgoing cable 8 signals whose character is determined by the signals in incoming cable I. Such a simple repeating equipment, however, is not capable by itself of performing any useful regeneration of the signals. The timing impulses necessary for regeneration are provided by a separate portion of the equipment known as the timer, shown within the dot and dash lines in Fig. 1. This timer is connected to the dot and dash locking and transmitting relays 3, 4, 5 and 6 over wire 9, in such a Way that the operating windings IUS, 205, |06 and 206 of the transmitting relays cannot be energized excepting at the moments when negative potential is connected to wire 9 by the timer.

'I'he timer itself has for its principal element a self-driven tuning fork II which is arranged to periodically connect wire 9 to a source of negative potential. The normal speed at which this fork operates is primarily determined by the natural resonance period of the fork itself, but is also capable of being slightly varied by means of fork speed rheostat III, which is connected in the self-energization circuit of the fork. By means of this rheostat the normal running speed of the fork is adjusted to be slightly faster than the average center-hole speed of the incoming signals.

In order to maintain the required synchronism between the fork and the signal, corrector pulse relay IIJ is provided. This relay is equipped with two operating windings III) and ZIO, as Wellas one biasing winding 3III. The two' operating windings III) and 2I0 are connected to the same contacts of receiving relay 2 which are used for controlling the re-transmitting equipment, previously described. These windings are so connected that the energization of either one of them will cause the armature of relay I to move to the right, the biasing winding being arranged to move this armature to the left. The relative strength of the biasing and operating windings are so chosen that the relay will be rapid not only in operation, but also in its return to normal. Therefore, no` matter how rapidly the armature of relay 2 may travel in moving from its left hand contact to its right hand contact or vice versa, relay I0 will not hold over and remain energized, but will release at the moment when the armature of relay 2 leaves one contact and will again re-operate when the armature of relay 2 arrives at the other contact. Thus, it will be seen that relay IIJ will operate or move from its left' to its right contact at the beginning of each dot or dash transmitted over the incoming cable to receiving relay 2, excepting in the case of a dot which immediately follows another dot, or a dash which immediately follows another dash.

Since the incoming signal consists predominantly of dots and dashes, with only a small percentage of zero impulses, and since the occurrence of two dots in succession or two clashes in succession is relatively less frequent than other combinations, it can be seen that relay ill will be operated by a comparatively large proportion of the signal pulses, thus providing a suicient number of opportunities for comparing the signal timing4 with the fork timing.

'I'he armature of relay I0 is connected through a two microfarad condenser 4I0 to a source of positive potential and the left hand contact of this relay is arranged to discharge the condenser through a suitable resistor 5I0. Thus, upon each operation of relay I0 a brief pulse of positive potential Ais transmitted out over the right hand contact of the relay. This impulse does not continue as long as the relay continues in the operated state but only occurs for a very short time, each time the relay actually operates. These pulses are used for comparison with a diierent set of pulses produced by the fork to determine whether or not the timing of the fork and signal differ by more than the tolerated amount.

The fork pulses which are used for comparison to as the fork-pulse delay rheostat.

with the above described pulses from relay I0, are not derived directlyfrom the fork contacts but from a fork pulse relay I5 which is operated under the control of the fork through a special delay chain I2, I3, I4. This chain determines how much delay will be provided between the closure of the fork contacts and the operation of the fork pulse relay and also independently determines the duration of the operation of this relay. Both of these time intervals can be readily adjusted and will remain exceedingly constantv at the value to which they are set.

In this special timing chain, I2 is a vacuum tube whose cathode is connected to a point of zero or neutral potential (designated I) in the drawings. The screen grid of this tube is connected through a suitable resistor to positive potential. The control grid 4l2 of this tube is connected through condenser II2 to a source of positive potentialthis condenser being shunted by an adjustable high resistance rheostat 2 I2, hereinafter referred Grid M2 is also connected through a suitable low resistance 3I2 to a switch 2I I, which may be connected to either an inner or an outer contact of fork II.

We will assume that the switch is connected as condition assumed, and shown in the drawings,

the potential of grid 4I2 will be highly negative with respect to the cathode of tube I2, and condenser II2 will be charged. Anode SI2 of this tube is connected to a source of positive potential through the winding of relay I3.

Under the control of the contacts of this relay I3 is vacuum tube I4 whose cathode is connected to neutral potential (i) and whose screen grid is connected through a suitable resistor to positive potential. Control grid 2M of this tube is connected to a source of negative potential through a variable high resistance rheostat Ill, hereinafter referred to as the fork-pulse duration rheostat. When relay I3 is operated, however, this grid 2I4 becomes also connected to positive potential through a two-microfarad condenser II3. Thus, at the moment of operation of relay I3, control grid 2H becomes strongly positive through the discharge of condenser H3 and then slowly returns to its normal negative potential as this condenser charges through rheostat H4. A suitable discharge resistor 2I3 is connected to the back contact of relay I3 in such a way as to discharge condenser I I3 whenever relay I3 returns to its back contact. Anode 3M of this tube is connected through the winding of fork-pulse relay I5 to positive potential, the connection being arranged to pass also through relay I3. The above described chain of apparatus II, I2, I3, Il and I5, together with the associated resistors and condensers, serves to cause the operation of fork-pulse relay I5 in response to the vibrations of fork II. The delay interval between the opening of the outer contact of fork II and the operation of relay I5 is adjustable-by means of fork-pulse delay rheostat 2 I2. The duration of theoperation of relay I5 is separately and independently adjustable by means of fork-pulse duration rheostat IM.

The* back contact of relay I5 is connected through a protective resistance II5 to negative potential so that normally, upon the operation of corrector pulse relay I0, condenser M0 will be discharged through this resistance H5. The

front contact of relay I6 is connected to the left hand winding 'oi correction pick-up relay I8. Pick-up relay I8 is provided with only one contact in order to make it quick acting. Thel armature of this relay I 8 is connected to a source o! positive potential and its single front contact is connected to its own locking winding I I 6, through the winding of auxiliary correction relay I'I and wire 20 which extends to the bias correcting relay, later to be described. Auxiliary correction relay I1 is provided with two contact levers III and 2I1. Lever 2II is not absolutely essential to the operation of the device but is merely provided to insure reliability. This lever cooperates with its back contact to open the connection of discharge resistor 2Il described above, for the purpose of preventing an'absolute tie-up in case the front and back contacts oi' relay I8 become short-circuited by thin lilaments oi' welded metal. Ordinarily a welded short circuit of this'type is only temporary and will disappear after a few openings and closures of the effected contacts. Because of the nature of the present circuit, however, it would be possible for such a short c ircuit at the pint mentioned to tie'up the system so that no further contact motions would occur; thus, the diillculty would not clear itself. By the provision of lever 2I'I and its back contact, such a tie up is prevented. Lever III is connected to negative potential and the front contact associated with this lever is connected through an adjustable rheostat 3II to the driving magnet of fork Il. Since this connection does not pass through the outside contact of the fork itself,

the closureof lever II1 against itsfront contact will .provide an uninterrupted energization of the fork magnet for the duration of the closure. The characteristics of the fork are such that this energization will not only decrease the amplitude of the fork vibrations but will also slightly slow up the vibrations of the fork. Rheostat 3II enables the intensity of this slowing action to be regulated and is hereafter referred to as the fork-slowing intensity rheostat. I'he back contact of lever I I1 is used to control a third vacuum tube I8 whose function is to determine the duration of the corrections applied to the fork.

'I'he cathode of tube I8 is connected to neutral potential (i) while its screen grid is connected through a suitable resistor to positive potential. The control grid II8 of this tube is connected to a source of positive potential through a condenser 2 I8 which is shunted by a variable high resistance rheostat 3I8 (referred to as the fork-slowing duration rheostat). -This grid is also connectedthrough a suitable low resistance I8 to the backv contact of lever II'I of the auxiliary correction relay I'I. Normally, therefore, the potential on grid I I8 is highly negative relatively to its cathode. Anode 5I8 of this tube is connected to positive potential through the winding of correction terminating relay I9. This relay I9 is lprovided with a singlefront contact which is connected so that upon the operation of relay l5, it short circuits the locking or right hand winding of pick-up relay I6. i

In addition to the re-transmitting equipment and the timing equipment described above, there .is provided some further apparatus shown on the drawings at the left of Fig. 2 and marked Bias equipment." Operating windings I25 and 225 of the bias correcting relay 25 are connected in series with windings IIII and 2I0 of relay I0 so that this relay 25 is operated from the contacts of the receiving relay 2. Because of the reversed equipment.

relationship of these windings I2! and 228, however, the bias correcting relay operates in a somewhat diierent manner from the corrector pulse relayIII-belng operated to the left in response to a dot signal and to the right in response to a dash signal. Since relay 25 has no bias winding, and since it is of the two-position type whose armature is incapable of remaining midway between its contacts, the relay will, during nocurrent or zero signal pulses, remain in the position to which it has last been moved. The armature of this relay 25 is connected to wire 28 which, as shown in Fig. 1, receives a pulse o! positive polarity each time the correction pickup relay operates. 'I'he contacts of this relay 2l are connected through its respective locking windings 325 and 425 to two terminals of the automatic bias corrector schematically illustrated below the relay. 'I'his automatic bias corrector is of the type fully described and shown in Patent No. 1,929,879 to A. F. Connery.

The function of this automatic bias corrector is to compensate for unsymmetrical conditions of the line circuit or of the transmitting or receiving This is performed by biasing the receiving relay 2 (by means of an auxiliary winding or its normal receiving winding). The automatic bias corrector acts to change the amount of bias so applied, by small steps between a maximum value of dash bias and a maximum value of dot bias. In response to a positive pulse upon its left hand terminal (which is produced in response to the occurrence of a correction during a dot signal as hereinafter explained) the automatic bias corrector moves one step in the direction of increased dot bias (or decrease dash bias). In response to a positive pulse on its right hand terminal (which is produced in response to a correction duringv a dash signal as hereinafter explained) the automatic bias corrector movei one step in the direction of increased dash bias (decreased dot bias). Thus, if the corrections of the fork at a given time are occurring primarily on dot signal pulses, the bias applied to the receiving relay will be cumulatively altered in the dot direction until the symmetry of the signals i: so restored that corrections in general take place equally on dots anddashes.

The above detailed description of the apparatus and its interconnections not only provides ar adequate disclosure of how to construct the preferred embodiment of the present invention, bui almost sufces to make its operation obvious. Foi completeness, however, a brief description ol' th( operation will be given.

vIn the timing equipment the self-driving tunI ing fork II has been adjusted so that it is vibratI ing at a normal speed slightly higher than th( average center-hole speed of the incoming signal Simultaneously, the corrector pulse relay Il i operating sporadically under thecontrol of thl dots and dashes of the signal as received by rela: 2. For deiiniteness in my description, it will b arbitrarily assumed that the desired relation be tween the fork vibrations and the operations o relay IIJ is as follows: the fork just commences t open its left o uter contact at the instant whicl y corresponds to the center of anincoming signa pulse as received by relay 2. It will be also arbi trarily assumed that at the present time this de sired timing relation is exactly fulfilled.

The instant when fork II opens its left han( outer contact will be employed as the refereno point from which to compute time for fork II a well as for the chain of apparatus I2, I3, I4, I

that one complete cycle of the fork equals 360.'

Thus the opening of the left hand outer contact of the fork occurs at fork time At the instant of the opening of the above noted contact (that is, at zero degrees) the charge on condenser II2 commences to leak oiI through rheostat 2I2. Thus the potential of grid I2 rises exponentially at a rate determined by the forkpulse delay rheostat 2I2; After a certain interval, the potential of grid 4I2 is suillciently high so that the space current of tube I2 operates relay I3. I'his relay will be assumed to close its make contact at K degrees of fork time. At the instant when the make contact of relay I3 closes, grid 2H of tube I4 becomes positive through con- .denser II3. As a result of this positive potential on grid 2 I4, the space current of tube I4 becomes more than suillciently great to operate the, forkpulse relay I5. This relay I therefore closes its make contact at a time only slightly later than K'; we will call the moment of this contact closure fork-time K. The positive potential on grid 2H, however, exponentially decreases commencing from the instant when it is applied (from fork time K') because of the charging of condenser II3 through rheostat Ill. After an interval, therefore, the potential of grid 2li becomes sumciently negative to cause the release of relay I5. 'I'he time at which this relay in releasing leaves its make contact will be called fork time C. meansof the fork-pulse duration rheostat" II4.

From the above description it will be seen that the armature of relay I5 remains closed against its make contact during the interval from K to ,C. Both the duration of this interval and the -time of its commencement are accurately and independently adjustable. are determined by the charging or discharging rates of condensers through adjustable resistances. 'Ihe inherent accuracy of such an arrangement is enhanced by the fact that the ex- .ponential charging and discharging curves are not used in the vicinity of their asymptotic endregions (since the negative and positive potentials available for the control grids of tubes I2 and I4 are designed to be far in excessief the values acquired for complete cut-off and for relay operation respectively).

Independently ofA the above traced train of events, corrector pulse relay I0 is simultaneously operated in response to the incoming signalas received by relay 2. As explained previously, this relay I0 does not operate in response to every pulse but the sporadic operations of this relay when they do occurare precisely timed with respect to the vibrations of fork Il except for two factors:

(l) The irregularity of individual signal pulses with respect tothe average center-hole speed of the signal.

(2) The deviation of the fork from its normal time relationship with thecenter-hole speed of the signals.

So long as the sum of these factors does not exceed a predetermined tolerated amount, correction pick-up relay II will not be actuated. 'I'his tolerated amount of phase difference between fork II and relay l0 is determined by the length of the time interval which has been called K. Normally, when the desired relationship between the signal and fork exists, the operations ot correction pulse relay I0 will occur shortly before This time is accurately adjustable byl 'Ihese time intervals the operations of fork pulse relay IB. In other words relay I0 will deliver its brief surge of current before fork time K. In this case, the condenser 4I0 will discharge through resistance III and therefore pick-up relay Il 'will not be energized.

Assume now that the fork gradually Igains in phase with respect to the incoming signal (because of its slightly higher frequency). Finally, the fork will get so far in advance of its proper timing relative to the signal that fork pulse relay I5 will'operate before the corrector pulse relay Il.

In this case, upon the operation of relay I0 pickup relay I6 will be operated, locking itself and energizing auxiliary correction relay I'I in an obvious manner. The operation of auxiliary correction relay I1 will apply to the drive magnet of the fork an uninterrupted energization superposed on the regular self-interrupted driving energization. Because of the characteristics of the fork,

, this uninterrupted energizatlon will slightly slow down the rate of vibration as long as it continues to be applied. 'I'he operation of auxiliary correction relay II will also permit condenser 2|! to discharge through rheostat 3 I8 so that the potential of grid II8 will exponentially rise. After an interval of time determined by the adjustment of rheostat 3I8, the potential of grid IIB will be suillciently positive so that the space current of tube Il will operate relay I9. Finally, the operation of this correction terminating relay I9 willv short circuit the locking winding of pick-up relay IB thus permitting the latter to release. 'Ihis release of relay I8 causes the release of relay I1, the termination of the fork-slowing current, and the restoration of grid II8 to its normal potential. The restoration of this grid to normal releases relay IS so that the correction equipment is all in condition for another operation.

In the above description of the operation of the timing equipment there has been described how an unusually retarded signal cooperates with a fork which has slightly advanced in phase to cause a correction which slows down the fork for a predetermined duration of time. The intensity oi the slowing or braking current is also predetermined, so that the net result of the correction is to setback the phaseof the fork by a deilnite amount, generally of the order of 15 or 20. If, in some manner, the fork is so far ahead in phase that it requires more than this amount of correction, a second correction will immediately be applied to it at the next operation of corrector pulse relay I0.

ordinarily with this system the signals which cause corrections to take place are those signal* elements whose eilective starting points are unusually retarded with respect to the general average center-hole timing of the incoming message. 'Ihe unusually retarded signals areln general produced by the transmission of a dot immediately following one or more dash signals or by 25 to the automatic bias corrector. Relay 25'is, of

course, operated to its left hand position by dots and toits right hand position by dashes. Therefore, in the above assumed case in which dots were more favorably received so that the corrections took place predominantly at the time of reception of dashes, the pulses received by the automatic bias corrector will be predominantly on its right hand terminal. This will cause the compensating bias applied to receiving relay 2 to be cumulatively altered in such a direction as to be more favorable for the reception of dashes. Similarly, if the predominating signals are dashes (so that the late signals which cause correction are mostly dots) the automatic bias corrector will be actuated mostly by signals on its left-hand terminal and will therefore cumulatively vary the bias in the direction which is most favorably for dots.

The operation of the re-transmitting equipment itself is very simple. In accordance with the signal received by relay 2 dot or dash locking relay 3 or l is operated. Then, at about the center of the signal pulse, a timing impulse is received on wire 9 from the tuning fork II. This4 impulse on wire 9 normally locks the dot or dash locking relays in whatever positions they then occupy, and energizes the appropriate windings of relays 5 and 6 to cause these to take up positions corresponding to relays 3 and 4 respectively. When the brief pulse on wire 9 terminates, relays 3 and 4 are again free to move in accordance with the incoming signals but relays 5 and 6 will now remain in their new positions until the arrival of the next pulse on wire 9. Thus, it will be seen that this regenerator equipment determines the character of the pulses transmitted (whether plus, minus, or zero) by means of the character of the incoming signal pulse. This determination is effective at a time which is about the center of the incoming pulse so as to be less affected by distortion. Furthermore, it will be noted that the time at which the outgoing pulses start and end is not determined from the incoming signal but from the timing device. Thus, the signals transmitted out over the outgoing cable 8 are not only re-shaped so as to have square tops but are also re-timed so as to have a uniform, even space from the commencement of each signal element to the commencement of the next one. It will also be noted that these signals are slightly shifted with respect to the incoming signals, since each transmitted pulse commences at approximately the4 center point of the incoming signal pulse; this however is ordinarily of no consequence.

For best operation, it has been fovund that the fork speed should be set approximately one cycle per second faster than the average centerhole speed of the incoming signals. The forkslowing duration rheostat should be adjusted so that the correction will last several fork cycles (say 5 or 10). The, the fork-slowing intensity rheostat should be adjusted so that the total phase retardation caused by one correction of the fork is of the order of 15 or 20. This will mean, of course, that approximately 18 to 24 corrections per second will take place during ordinary transmission.

'I'he fork-pulse delay rheostat is now adjusted to give the desired relation of the timing pulse on wire 9 with respect to the signals received by relay 2. By the inherent operation' of the fork correction apparatus the timing relation between fork Il and the incoming signals will be maintained such that normally fork pulse relay I5 will operate slightly later than corrector relay pulse I0. ,Therefore since the time of operation of fork pulse relay I5 is K after the open- 'ing of the left center contact of the fork, any

variation ofthe time interval K will ultimately result in a changein the timing relation between the vibrations of fork I I and the incoming signal.

The adjustment of fork pulse duration rheostat" II4 controls the duration of the fork pulse, i. e. the time during which relay I5 remains operative. This time should be longer than the ordinary variations between advanced signals and retarded signals.- For example, if some of the signals are transmitted 30"l earlier than the average and other signals are transmitted 38 later than the average, the duration of the fork pulse should be at least 68. On the other hand, the duration of the fork pulse should not be so long as to allow any possibility of extending over into the next following signal pulse, even if this signal pulse happens to be unusually early. For this reason (on the above mentioned assumption of 30 maximum leading distortion and 38 maximum lagging distortion) the fork pulse must be less than 292 in length. Also the total time C (which is the delay of the fork pulse plus the duration of the fork pulse) should be less than 360. With the above assumption of signal distortion, and the previous arbitrary assumption that 0 of the fork cycle occurs at the center of the average signal pulse, this will mean that the fork pulse should be less than 142 in length. It will thus be seen that the adjustment of the fork pulse duration rheostat is not at 'all critical unless the distortions encountered in the signal are unusually severe.

Although the above described embodiment of the invention comprises a fork Whose natural speed is higher than the average center-hole speed of the incoming signal, and a correcting system for the fork which acts to delay its phase by a predetermined amount, it is obvious that the converse system can be used in which the fork vibrations are normally slower than the average center-hole rate of the signal. In such a system the correcting signal must be arranged to set forward the phase of the fork (for example, by speeding up its vibrations for a certain length of time).

It will be noted in the above described embodiment the corrections occur when the interval between the opening of the left outer fork contact and the operation of relay I0 becomes greater than the time interval determined by the delay chain Il, I2, I3, I4, I5. It is obvious that without changing the spirit of the invention, the system could be arranged so that the correctionsl taire place when the interval between the fork vibration of the operation of relay I0 becomes less than the interval determined by the delay chain. In general, however, it is a feature of this invention to correct from one side only, i. e. to correct only when the interval between the vibration of the fork and the operation of relay Il) becomes unequal in one particular sense to the interval determined by the delay chain.

Also, it should be noted that while the above described embodiment of the invention employs a delay circuit between the fork contact and the s corrector pulse relay ill instead of under the control'oi tuning fork li (or both chains together might be used). Either of these arrangements is somewhat superior to the use of a delay chain in wire 8 .between the fork and the retransmitting 10 relays because the fork vibrations themselves are employed for timing the regenerator without the interposition of any apparatus.

What I claim is: l. In a telegraphic signal regenerator a receiving relay, a vibratory timing member, a

transmitting relay jointly controlled bysaid receiving relay and said member, a speed iniluencj ing magnet for varying the vibration ratepf said,

member, means for initiating corrections when 2 9 the assynchronism between the receiving relay and the vibratory member exceeds a certain value, a condenser, a resistor, a space discharge device vhaving a control grid, connections whereby the vpotential of said condenser is varied by current 2 5 through said resistor in response to the initiation of acorrectlon' by said initiating means, other Vconnections between said dischargeA device and said condenser such that the space current of said discharge device is varied in response to the po- 30 tentlal of said condenser andv means for controlling the energization of said magnet under `the control of said space current to vary the speed of said member for a predetermined time..

2. A telegraphic signal regenerator comprising 35 a self-driven vibrator, a magnet for iniluencing the speed thereof, a ilrst means operated respon- Asive to incoming signals, a second means operated in response to the motion oi' the vibrator, a space discharge tube coupled to said second 40 means, a partially reactive circuit having an adjustable time constant, connections between said space discharge tube and said partially reactive circuit whereby the current through said tube is controlled by said partially reactive circuit to 45 determine a denite time interval and correcting means for controlling the energization of said magnet in response to inequality in one sense by a predetermined amount of the time interval between the operation of said first and second 50 means and the time interval determined by said space discharge tube.

3. Atelegraphic signal regenerator comprising a self-driven vibrator, a magnet for influencing the speed thereof, a first device operated re- 55 sponsive to incoming signals, a contact device operated in response to the motion of the vibrator, a space `discharge tube coupled to said contact device, a partially reactive circuit having an adjustable time constant, connections be- 'tween said space discharge tube and said partially reactive circuit whereby the current through said tube is controlled by said partially reactive circuit to determine an adjustable time interval andcorrecting means for energizing said magnet in response to the condition'that the time.

interval between said ilrst device and said contact device is greater than-the time interval determined by said space discharge .tube and associated circuit. v l

4. A telegraphic signal regenerator comprising a self-driven vibrator, a magnet for influencing the speed thereof, a first device operated responsive to incoming signals, a second device operated in response to the motion of the vibrator, a space discharge tube, a partially reactive circuit having a predetermined time constant, connections whereby the current through said tube is controlled by said partially reactive circuit to determine a definite time interval, correcting means for controlling the energization of said magnet invresponse to an inequality of the interval between the operation of said first and second devices, and the time interval determined by said space discharge tube, a second space discharge tube, a second partially reactive circuit having an adjustable time. constant, connections whereby the current through the said second tube is controlled by said circuit to determine a second interval and holding means'to maintain for the duration of said second time interval the energization of the magnet which is caused by the correcting means.

5. A telegraph signal regenerator comprising a self-driven vibrator, a magnet for inuencing the speed thereof, a first device operated in response to incoming signals, a second device operated in response to the motion of the vibrator, corrector means for controlling energization of said magnet in response to a predetermined difference in time between the operation of said first and second device, means for determining said predetermined time difference comprising a space discharge tube coupled to said second device and a partially reactive circuit having an adjustable time constant coupled to said tube, and connections for energizing said corrector means in response to an inequality between the length o'f said time difference in aredetermined sense and the length of time determined by said adjustable time constant circuit.

ALDER F. CONNERY. 

